Effect of Opening Size in Unreinforced Masonry Walls Subjected to Lateral Loads: Computational Modeling and Code Comparison

Abstract

Perforated unreinforced masonry (URM) walls are used in most existing masonry buildings as structural and nonstructural elements. Depending on the size and position, openings may detrimentally affect the stiffness and seismic capacity of URM walls. This research investigates the structural behavior of perforated URM walls with different opening sizes and proportions subjected to lateral loading using the discrete element method (DEM). In the applied modeling strategy, masonry walls are composed of rigid blocks, where their mechanical interactions are simulated via point-contact hypotheses. Once the numerical approach is validated, parametric analyses are performed to better understand the effect of different opening sizes and their aspect ratios on the failure mechanism and shear capacity of perforated URM walls. The results quantify the lateral load–carrying capacity and demonstrate its inverse relationship with the opening size. Furthermore, a slight influence of contact stiffness (varied from 10 to 120 GPa/m) on the ultimate lateral load in DEM-based simulations is noted. Finally, the obtained shear force capacities are compared against the strength prediction equations provided in current US standards. In most cases, the predictions of the US standard provide conservative values relative to the DEM results.